Hungarian Cohort Finds Children With MIS-C Recover Heart Function Years After Illness

When a mysterious inflammatory illness began striking children weeks after SARS-CoV-2 infections in the spring of 2020, paediatricians around the world scrambled to understand a condition that seemed to turn the immune system against the body itself. Multisystem inflammatory syndrome in children, or MIS-C, quickly became one of the most feared complications of the pandemic’s early waves. Now, a retrospective cohort study from Hungary has followed dozens of affected children for nearly five years, and its findings offer a measure of reassurance: the dramatic cardiac abnormalities that characterised the acute illness appear to leave no lasting trace detectable on advanced cardiac imaging, and most children report a complete return to normal life.

The study, conducted by researchers at Semmelweis University in Budapest and published in BMC Pediatrics, analysed 54 children diagnosed with MIS-C between September 2020 and March 2022. The cohort, with a mean age of 9.0 years and a marked male predominance of 68.5 percent, reflected the demographic pattern seen in most international series of the syndrome. Nearly a third of the children, 17 patients or 31.5 percent, required admission to an intensive care unit during their acute illness, underscoring how severely this post-infectious condition can affect previously healthy youngsters. Every patient in the cohort survived, a statistic that speaks both to the natural history of the disease and to the effectiveness of the supportive and immunomodulatory treatments deployed against it.

Laboratory investigations during the acute phase revealed the hallmark of MIS-C: a ferocious systemic inflammatory response. The children showed markedly elevated levels of C-reactive protein, procalcitonin, interleukin-6 and ferritin, the molecular signatures of a cytokine storm in miniature. Cardiac biomarkers were frequently abnormal as well, signalling that the heart was a common target of the inflammatory assault. Serological testing confirmed prior SARS-CoV-2 infection in 48 of the 54 patients, an infection rate of 88.9 percent overall and 48 of 49 among those actually tested, consistent with the understanding that MIS-C is a delayed post-infectious phenomenon rather than a direct consequence of active viral replication.

The cardiac findings formed the clinical core of the study. Echocardiography performed during hospitalisation identified transient abnormalities in a substantial proportion of patients. Reduced left ventricular systolic function, the heart’s ability to pump blood effectively, was documented in 7 of 48 patients examined, or 14.6 percent, with the group’s mean fractional shortening measured at 38.7 percent. Valvular regurgitation, in which heart valves fail to close properly and blood leaks backward, and small pericardial effusions, collections of fluid around the heart, were also observed. Perhaps most concerning at the time were coronary artery abnormalities, detected in 8 of 48 patients, or 16.7 percent. Four of these children met the criteria for a small coronary aneurysm, a localised bulging of the vessel wall that echoes the vascular complications seen in Kawasaki disease, another paediatric inflammatory condition with which MIS-C shares striking similarities.

Treatment during the acute phase followed the emerging international consensus for MIS-C management. Intravenous immunoglobulin, the purified antibody preparation borrowed from Kawasaki disease protocols, was administered to 88.9 percent of the patients. Systemic corticosteroids were given to 83.3 percent, reflecting the growing evidence early in the pandemic that combining steroids with immunoglobulin could dampen the inflammatory cascade more effectively than immunoglobulin alone. Only three patients, 5.6 percent of the cohort, required biologic therapy, the class of targeted immunomodulatory drugs reserved for the most refractory cases. The high survival rate without any MIS-C-related mortality suggests that this layered treatment approach, escalated from immunoglobulin through steroids to biologics when necessary, was sufficient to control the syndrome in this population.

The most technically significant contribution of the Hungarian study lies in its use of cardiac magnetic resonance imaging, or CMR, for medium-term follow-up. Unlike echocardiography, which offers real-time views of cardiac structure and function but limited tissue characterisation, CMR can detect subtle myocardial injury, fibrosis and inflammation through techniques such as late gadolinium enhancement, in which a contrast agent highlights areas of scarring or damaged heart muscle. Half of the cohort, 27 of the 54 patients, underwent follow-up CMR, and the images were evaluable in 26 cases. The result was unambiguous: none of the scans showed any MIS-C-related abnormality. For a syndrome whose acute phase can involve measurable pumping dysfunction and coronary changes, the absence of persistent myocardial findings on the most sensitive available imaging modality is a genuinely encouraging signal.

Beyond the imaging data, the researchers captured something rarer in the MIS-C literature: patient-reported outcomes at a median of 4.7 years after diagnosis. Using a structured questionnaire administered between December 2025 and January 2026, the team assessed symptom burden, functional recovery, school attendance and healthcare utilisation among the families. Responses were available for 35 patients, 64.8 percent of the original cohort. Every single respondent had returned to full-time school attendance, the majority reported physical activity tolerance comparable to their pre-illness level, and the median overall recovery score was a perfect 4 out of 4. In a condition that once filled paediatric intensive care units and prompted urgent public health alerts, these medium-term data paint a picture of children who have, by and large, left the illness behind them.

The findings carry weight precisely because they address a question that has lingered since the pandemic’s early days. Acute MIS-C is undeniably dramatic, with fever, rash, gastrointestinal symptoms, shock and cardiac dysfunction converging in previously healthy children. But severity of the acute episode does not necessarily predict long-term damage, and the medical community has lacked robust longitudinal data on whether the myocarditis-like changes and coronary abnormalities seen during hospitalisation resolve completely or leave silent scars that could pose risks decades later. The Hungarian CMR results, showing no persistent myocardial abnormality in any of the 26 evaluable patients, directly address that uncertainty for this cohort, complementing smaller international follow-up studies that have reported similar patterns of cardiac recovery.

The authors are careful to acknowledge the limitations inherent in their design. As a retrospective, single-country cohort without a control group, the study cannot determine how much of the favourable outcome should be attributed to treatment rather than to the natural history of the disease. The follow-up questionnaire reached roughly two-thirds of the original patients, leaving open the possibility that families of children with lingering problems were over- or under-represented among respondents. And while CMR is highly sensitive, it was performed in only half of the cohort, meaning that subtle abnormalities in the other half cannot be formally excluded. These caveats do not undermine the central observations, but they frame the conclusions appropriately: within the limits of the data, MIS-C in this Hungarian cohort was associated with significant but reversible cardiac involvement and good medium-term recovery.

The broader significance of the study extends to how clinicians counsel families facing a new MIS-C diagnosis. Parents told that their child has developed coronary aneurysms or a weakened heart muscle in the wake of a coronavirus infection naturally fear permanent damage. Evidence that, years later, cardiac magnetic resonance shows no residual abnormality and that children are back in school and on the sports field provides the kind of concrete, longitudinal reassurance that acute-phase data alone cannot supply. As the pandemic recedes into history, studies like this one are assembling the long-term record of COVID-19’s effects on children, and for MIS-C at least, the Hungarian experience suggests that the body’s inflammatory storm, however violent, usually passes without leaving a mark on the heart.

Subject of Research: Medium-term cardiac and functional outcomes of multisystem inflammatory syndrome in children following SARS-CoV-2 infection

Article Title: Clinical characteristics, cardiac involvement, and medium-term outcomes of multisystem inflammatory syndrome in children: a Hungarian retrospective cohort study

Article References: Clinical characteristics, cardiac involvement, and medium-term outcomes of multisystem inflammatory syndrome in children: a Hungarian retrospective cohort study. (n.d.). https://doi.org/10.1186/s12887-026-07705-6

Image Credits: AI Generated

DOI: 10.1186/s12887-026-07705-6

Keywords: MIS-C, SARS-CoV-2, cardiac involvement, cardiac magnetic resonance, coronary artery aneurysm, intravenous immunoglobulin, corticosteroids, paediatrics, inflammation, long-term outcomes, echocardiography, patient-reported outcomes